Re: [PATCH 1/1] mmc: host: enable OMAP DMA engine support for omap hosts by default

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Fri, Aug 24, 2012 at 09:51:15AM +0200, Peter Meerwald wrote:
> the commit just sets CONFIG_DMA_OMAP=y and CONFIG_DMADEVICES=y in 
> omap2plus_defconfig; this does not help people updating the kernel while 
> keeping the config, nor does it help people in configuring the kernel
> 
> there is a dependency (at least for beagleboard) between MMC_OMAP_HS and 
> DMA_OMAP, and I think this should be made explicit

Well, this is where stuff starts to get really yucky, because that
means if you have DMA_OMAP as a module, you have to have MMC_OMAP_HS
as a module too.  Or vice versa.  Which is a real pain for further
development of DMA_OMAP.

Whatever, the solution here is NOT to add select statements to the
Kconfig to force DMA engine support and DMA_OMAP to 'y' for OMAP.
The best solution is for MMC_OMAP_HS to depend on DMA_OMAP, but that
will just mean that you'll end up with MMC_OMAP_HS disabled in your
config witout DMA engine support.  Another less desirable solution
is to have MMC_OMAP_HS select DMA engine and DMA_OMAP.